We were wondering if there is an algorithm that can be used to determine how far you've moved in any direction using the encoder values of the motors on a mecanum drive.
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The Mag Encoder is a sensor that measures the rotational position and velocity of the shaft driving your mechanism. After releasing the Mag Encoder a few years ago, we received a ton of positive feedback from the FRC community. However, you also told us that there was not an easy way to actually mount the mag encoder to a ball shifter. No need to modify any of the Ball Shifters that you already own!
Now you can easily add a Mag Encoder to your ball shifter, and it only takes a few minutes to install.
View Details. The VersaPlanetary Lite takes everything you know and love about the VersaPlanetary V2, and puts it into a lightweight plastic form factor. The VersaPlanetary Lite uses a plastic housing and ring gear, and the existing gear sets from the VersaPlanetary. One of its cooler features is that you can mix and match components from the original VersaPlanetary, and the VersaPlanetary Lite.
For example, you could use a plastic input and output with a metal ring gear, or a metal input and output with a plastic ring gear.
Changing PID Coefficients
An assortment of gear types providing the maximum versatility of gearing options to users. These gears have a Diametral Pitch of 32, which allows for reductions in smaller areas. They are also pocketed for maximum weight savings. Great for lighter load applications and smaller robots! Available in high-strength black anodized aluminum or lightweight plastic, the VersaRoller system enables you to easily create the solution for your roller needs.
This allows users to create custom length output shafts that are longer than a standard set length. The VersaBlock easily bolts on to the outside of the pre-drilled VersaChassis tubing - no precision machining needed to achieve a precision aligned drivetrain.
VEXpro Sprockets are custom manufactured out of high strength aluminum, black anodized anodised for superior performance. Developed in collaboration with West Coast Products, Straight Flex Wheels are for use with intakes, conveyor systems and shooters. Flex Wheels are made of a super tough custom blend of silicone rubber - different than any other flexible or compliant wheel currently used by FTC or FRC teams. Each of our four wheel diameters are offered in 3 different durometers: the super soft 30A in light gray, the medium hardness 40A in dark gray and the hardest 60A in black.
The varying hardnesses can be used to change the traction and compliance of your mechanism. This also allows you to stretch these wheels over a VersaRoller tube to create a strong and lightweight roller. Roller Chain in 10 foot lengths for use with any 25 or 35 Sprocket.Want to contribute information related to another method, or make a correction? Let us know. Optionally, we may wish to attach an encoder to measure the movement of the motor. We just need a separate encoder cable to plug it in.
If we use the Modern Robotics modules, the motor attaches to one of the two motor ports on the motor controller using the powerpole connectors. Then, a pair of wires with powerpole connectors run from the power port of the motor controller to one of the ports on the PDM. We probably want to declare a class-level variable for each motor. Make sure to name variables something relevant to what the motor does:.
During the init process or before waitForStart in a Linear OpMode we should initialize your motor variable.
Through Bore Encoder
Inside the get " We might want to reverse the direction of a motor for example, if we have left and right drive motors facing opposite directions. We can do that right after initializing the motor:. One of the most common ways to run a motor is to set power directly:. We can use any decimal value between Setting the power back to zero will make the motor stop.
If we want to reset the encoder back to zero, we can do that:. Often, one of the first things we want to do is drive using the joysticks on a gamepad. This is a multi-step process, if we do it correctly. This is no longer necessary, as the gamepad class does this for us. Alternatively, we can reverse the right drive motor s and remove the negative signs when reading the gamepad input. As mentioned above, there are other ways to use the motor. During normal operation, we tell the motor our desired power.
The output of the motor at a given power will depend on the motor, its internal gearbox, and its work load. We can also change the motor to run in terms of speed or target position. For example, if the motor is really close to its target position, it will use a small amount of power to advance or retreat. Whatever we give to setPower is supplied directly to the motor. This variable is set by the motor profile we choose while configuring the Robot Controller.
It is therefore quite important to choose the correct motor type. If we know the encoder value we want the motor to reach, we can ask the controller to take it there using PID. In the init phase, include the following after we initialize the motor variable:.
Now, we need to give the motor two pieces of information: where to go, and how fast. We can change one without changing the other:.
The motor controller will automatically choose the correct direction to move.
FTC Tetrix Encoders
When the encoder value gets close to its target, the motor will automatically slow down, and correct itself if it moved too far. If another force like a robot, or gravity pulls the motor away from its target position, the controller will attempt to correct for it. If we forget to reset the value at the beginning of the program, or if you reset it while a target is set, there may be unintended consequences.
Be safe! Intuitively, this mode causes the motor to run based on speed instead of power. Using PID control, the input you give to setPower will be interpreted as a a percentage of some maximum speed.Throughout our testing, we have found that the encoders we use on our FTC robot will occasionally output a random, erratic value. The result of this is that, while driving in autonomous, the robot will stop early in one of its moves. These are unpredictable incidents and only happen in one move in every runs.
This value is usually significantly higher than the surrounding values. The values would then go back to their usual or expected range after a couple of milliseconds.
Now the problem with this is that whenever we would get one of these values, our autonomous driving would end early because the program thought that it had reached the target value, i. Because we were able to identify this problem, we developed a very simple solution to solve it.
Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. To identify if your robot is suffering from these sporadic encoder values, there is a simple test and we recommend implimenting the solution anyway so that if you ever do see it, it wont affect you.
First, write a simple autonomous that just will spin the wheels forever and display encoder values.
Now, when you run this program with the NXT connected to your computer, the debug stream should fill up with values that you can then import into excel.
Don't expect to see the sporadic values every time. Remember, we found them once every long autonomous runs. So if the values only appear for a few milliseconds, but still get caught and trigger our program to move on, how do we ignore the values we don't want? There is a simple solution. We can do one of a couple things. If our robot is driving to an encoder distance, and we see a value greater than our target, we wait a few milliseconds and check again.
This gives the encoders time to get back to their normal values. If the current encoder value is less than the target we keep driving.
However, if the encoder is still greater than the target, we know that we have actually got our target distance and move onto the next step in our autonomous. The first graph is what the encoder values should look like, with the motor running at a constant speed. The increase is linear.
The second graph is shows the sporadic value as a spike down. The sporadic values can be up or down, in this case, it was down. This is the movement function we use in autonomous. For this to work, an active heading is required, as well as a target heading.
The way this works combines the current encoder values to get a running total as the robot drives.Blocks Programming Reference Materials. Questions about Blocks Programming can be posted using this Blocks Programming sub-forum. Before posting a new question please review previous posts as your question may already be answered. Version 3. Modern Robotics has posted a diagnostic program called Core Device Discovery that you may find useful. Sample Robots and Hardware Information.
Information about FTC Field. Using Java is a good option for teams that have a coach or mentor with Java expertise. App Inventor and Blocks Programming are good choices for new teams and teams where the programming will be done by members without prior Java experience. There are three ways to print an op mode program using Windows.
In all three cases you start by displaying the op mode program using your web browser. Save the PNG image file on your computer. If you have a Windows computer, select Paint in the Windows Accessories sub-menu. From Paint open the PNG file. Use File-Print-Page Setup and then use the Scaling feature to select enough pages to assure the blocks in your op mode will be large enough to read.
Then print the program from your browser. Then start the Windows Paint program. In Paint use the Paste button from the Home menu or just press control-V to place the screen shot on the Paint canvas.
Per above you may need to switch your computer from being connected to your RC phone to being connected to your LAN to do this. You may want to move your op modes from the first Robot Controller RC phone to another either because you are placing a phone or you want to have a back-up phone at a competition. If so, you can proceed as follows:. Select Open. As discussed earlier, there are over a dozen sample op modes available from a drop-down menu when you create a new op mode.
Here are some additional sample op modes. You can download them to your computer by right clicking and then use the Upload Op Mode button on the Blocks main menu to add them to your list of op modes.Motor Programming in Blocks
Review the comments in each sample for information on connecting motors and sensors and setting up a matching config file. All of these op modes are intended to be used during the Autonomous period. Display the op mode by selecting it from the list after you have uploaded it. If it is labeled as TeleOp to the right of its name, change it to Autonomous and Save it.
This will cause it to correctly appear in the left menu on the Driver Station menu. Support for Blocks Programming If you would like to be added to an email list on Blocks Programming or have questions, send email to ftcblockshelp ortop. You can unsubscribe anytime.The cookie settings on this website are set to 'allow all cookies' to give you the very best experience. Please click Accept Cookies to continue to use the site. The REV Through Bore Encoder is specifically designed with the end user in mind, allowing teams to place sensors in the locations closest to the rotation that they wish to measure.
This rotary sensor measures both relative and absolute position through its ABI quadrature output and its absolute position pulse output. Absolute pulse input is not supported. Do not disassemble the sensor. Disassembling the Through Bore Encoder will dereference the zero position with the physical case notch.
It is not possible to recalibrate the zero position as it is permanently saved inside the sensor at the factory. Please contact us if you have any questions or concerns regarding the pulse resolution. You save. Current Stock:. Quantity: Decrease Quantity: Increase Quantity:. Specifications Input Voltage: 3. Alternate Encoder Adapter - 2 Pack. NEO Brushless Motor.This means that if you set a target speed, the motor controller will apply whatever power necessary within its safety limits to achieve the desired speed.
They are underrated by many FTC teams and are a valuable tool, if nothing else. It will also show you how to safely remove an encoder from a burned out motor. You will need: 1.
HiTechnic Motor Controller 4. NXT Brick 5. Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson.
So to begin, we just need the motor and the encoder pack. The encoder should come in several pieces. Take the one that is flanged with screw holes and insert it onto the motor shaft.
There should be two small screws in the pack use a small philips head screwdriver to carefully attach the encoder base to the motor. NOTE: it is important not to strip or round out the heads of the screws, these can be reused if the motor burns out! Now that the base is secured, carefully and without touching the flat parts, push the silver disc onto the shaft, black side towards the rest of the encoder. This is where the small, black, plastic disc that comes in the encoder pack is so useful.
This is actually a spacing tool. Use the tool to push down the optical disc until the black plastic touches the clips on the encoder base. Now the disc is at the optimal spacing for the encoder to work. Next, we just need to put the cap on the encoder. This protects everything, controls ambient light, and keeps dust and gunk out of the whole thing. This is where the we start putting things together in a state where we can run the motor.
The Encoder wire is the most delicate. The small white end goes into the encoder itself. If you will look closely at the encoder wire, there are two little bumps that stick out of the encoder end.
Those go facing towards the wall of the plug.